Space Shuttle Discovery turns the corner on the crawlerway leading to Launch Pad 39B in the background.

Space Shuttle Discovery turns the corner on the crawlerway leading to Launch Pad 39B (in the background). The rollout is an important step before launch of Discovery on mission STS-121 to the International Space Station. First motion of the shuttle leaving NASA's Vehicle Assembly Building was at 12:45 p.m. EDT. Discovery's launch is targeted for July 1 in a launch window that extends to July 19. During the 12-day mission, Discovery's crew will test new hardware and techniques to improve shuttle safety, as well as deliver supplies and make repairs to the station. Photo credit: NASA/Dimitri Gerondidakis